When invasive diagnostic or therapeutic procedures are to be performed which penetrate the skin, the health worker must accurately define the targeted area and designate a preferred point of entry. This is usually accomplished by a combination of visual inspection and palpation, followed by appropriate antiseptic procedures.
Various specialized devices are employed to enter subcutaneous tissues, blood vessels, muscles and other structures accessible through the skin, to obtain blood samples and biopsy specimens, or for the administration of medications, nutrients, blood transfusions and intravenous fluids. Such devices and their commonly associated components may include hypodermic needles, syringes, cannulas, vacuum tubes, catheters, probes, scalpels, biopsy punches and the like, depending upon the required diagnostic or therapeutic applications desired.
A variety of anatomical areas may be selected, depending on the particular requirements. For example, the hands and arms are usually preferred areas for the retrieval of blood specimens or for the placement of intravenous lines to administer transfusions, fluids, medications and selected diagnostic agents.
Considerable care and precision are required to ensure accurate instrument placement within the constraints of strict antiseptic protocol. Selected sites are generally targeted and localized by means of visual inspection and direct palpation. Because spatial memory is notoriously transient and imprecise, recall is often reinforced by accessible landmarks such as skin creases, scars, blemishes and area of local pigmentation capable of providing convenient points of reference and supportive visual cues.
In the absence of reliable visual information, repetitive palpation is usually required for precise orientation. Once a target is selected, antimicrobial procedures are instituted to render the area antiseptically clean This is generally accomplished by washing and the application of germicidal agents such as alcohol and iodine. After an antiseptic barrier has been established, operators must depend on prior orientation and supportive visual cues to delineate a final approach to the targeted site. Repetitive palpation at this time runs the risk of contaminating the antiseptically prepared area and thus is to be avoided. However, since spatial orientation is usually transient and uncertain, particularly in the absence of guiding landmarks, repeated palpation is often attempted even though additional manipulation presents needless opportunities for the transfer and dissemination of pathogenic microorganisms.
Such breaches of antiseptic protocol can be crucial for hospitalized patients who are exposed to repeated blood tests, multiple injections, continuous intravenous infusions and similar invasive procedures by doctors, nurses and technicians working in a potentially infectious environment under less than ideal conditions.
Thus a hand-held device that conveniently and temporarily impresses distinctive markings into the surface of the skin capable of accurately defining a selected target and directionally guiding an operator to a designated site-of-entry, without endangering antiseptic safeguards, offers significant advantages in safety and precision over methods and means heretofore employed.